The vertebrae in a patient's spinal column are linked to one another by the disc and the facet joints, which control movement of the vertebrae. Each vertebra has a pair of articulating surfaces located on the left side, and a pair of articulating surfaces located on the right side, and each pair includes a superior articular surface, which faces upward, and an inferior articular surface, which faces downward. Together the superior and inferior articular surfaces of adjacent vertebra form a facet joint. Facet joints are synovial joints, which means that each joint is surrounded by a capsule of connective tissue and produces a fluid to nourish and lubricate the joint. The joint surfaces are coated with cartilage allowing the joints to move or articulate relative to one another. In combination with the intervertebral disc, the two facet joints form the spinal three-joint complex.
Diseased, degenerated, impaired, or otherwise painful facet joints and/or discs can require surgery to relieve pain or restore function to the three-joint complex. Subsequent surgery may also be required after a laminectomy, as a laminectomy predisposes the patient to instability and may lead to post-laminectomy kyphosis (abnormal forward curvature of the spine), pain, and neurological dysfunction. Current clinical data have suggested that degeneration of one member of the three joint complex, that is either the discs or the facet joints, contributes to the degeneration of the other. While implants are available for replacing either a diseased disc or the facet joints, there are no implants that can be used to replace the entire spinal three-joint complex.
Accordingly, there remains a need for improved systems and methods for repairing and/or replacing the spinal three-joint complex.